Samples for microstructure analysis were collected from the HPP treated salmon pieces using a cork knife, 11 mm in diameter.They were embedded in plastic tubes 15 mm in diameter, 30 mm length (Kartell, Novigilo, Italy) containing optical coherence tomographical (OCT) compound (embedding medium) (Tissue Tek,Sakura, Torrance, CA) and frozen in liquid nitrogen. Freezing (below80 C) occurred in approximately 40 s.